* Bugfix import the _() translation in mixins.

src/events/mixins.py

@@ -2,6 +2,7 @@
 from django.db.models import Q
 from django.http import Http404
 from django.shortcuts import get_object_or_404
+from django.utils.translation import ugettext as _
 
 from . import models
 

src/membership/templates/membership/membership_form.html

@@ -17,18 +17,22 @@
 </p>
 </fieldset>
 </form>
-{% endblock %}
 
-{% block javascript %}
-$(function() {
-    $( "#id_birthday" ).datepicker({
-      changeMonth: true,
-      changeYear: true,
-      dateFormat: 'yy-mm-dd',
-      yearRange: '-50,0',
-      firstDay: 1
-    });
-  });
+<script type="text/javascript">
+function togglePersonalData(event) {
+    var membership = document.getElementById("id_membership").checked;
+    var input_elements = ["id_first_name", "id_last_name", "id_birthday"];
+    for (var i = 0; i < input_elements.length; i++) {
+      element_id = input_elements[i]
+      element = document.getElementById(element_id);
+      element.disabled = !membership;
+      if (membership == 0) {element.value = ""};
+    };
+};
+
+document.addEventListener('DOMContentLoaded',function() {document.querySelector('#id_membership').onchange=togglePersonalData;},false);
+togglePersonalData();
+</script>
 {% endblock %}
 
 {% block buttonbar %}{% endblock %}